Motor compressor



April 9, 1935. R. P. PESCARA 1,996,973

MOTOR COMPRESSOR Filed Jan. 5, 1933 3 Sheets-Sheet 1 INV ENTOR.

Raul Pateras Pescara ATTO HEY April R. P. PESCARA 1 1,996,973

MOTOR COMPRESSOR I Filed Jan. 5, 1935 3 Sheets-Sheet 2 M INVENTOR Raul Pareras Pescara QM a Quiz;

April 9, 1935. R. P. PESCARA MOTOR COMPRESSOR Fiied Jan. 5, 1933 3 Sheets-Sheet 3 I I 1' m1 $9M N Afforzzgs:

Patented Apr. 9, 1935 UNITED STATES PATENT OFFICE.

MOTOR COMPRESSOR Raul Pateras Pescara, Paris, France Application January 5, 1933, Serial No. 650,348

4 pressors of the type in which two opposed motor pistons are actuated directly by the internal combustion of a fuel.

In machines of that type, the inner ends of the pistons reciprocate in a motor cylinder into which the fuel is injected and in which it is sub- 1 sequently ignited, the whole working on the two stroke principle. The outer ends of the pistons reciprocate in a fiuidtight manner in two compression cylinders respectively disposed on either side of said motor cylinder and coaxially therewith. The return stroke of the pistons is caused by the expansion of the air cushions that remain in the clearancespaces of said cylinders at the end of the outstroke.

The chief object of the present invention is to provide a motor compressor of that type in which there is no risk of leakage through the inlet valves of the compressioncylinders during the period of time for which there are high pressures in said cylinders.

According to my invention, I obtain this result by disposing the inlet valves in a chamber placed laterally with respect to the compression cylinders and communicating therewith through a port that is covered by the piston during the periods of the compression and expansion strokes for which the pressure in the compression cylinder is very high. I

Another object of my invention is to provide a compressor of the type above referred to in which air is allowed to enter into the compression.

cylinder during the instroke thereof as soon as the pressure in said cylinder has fallen back to the atmospheric pressure, in spite of the above described arrangement of the inlet valves.

According to my invention, I obtainthis result by providing in each compression piston a conduit connecting the outer face thereof with a point of its cylindrical wall, said conduit'being provided with a supplementary inlet valve.

These and other objects of the present invention will be better understood from the following description of a preferred embodiment of my invention, with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is an elevational view, partly in section, of a motor compressor according to the present invention; 1

Fig. 2 is a horizontal axial section of said motor compressor;

Fig. 3 is a composite'view the right hand side of which is a section on the'line AB of Fig. 1

July 5, 1932 (01. 230-56) .and the left hand side of which is a section on the line CD of Fig. 1;

Fig. 4 is a diagram illustrating the .operation of the compressor;

Fig. 5 shows another embodiment of the pistons including an auxiliary inlet valve;

Fig. 6 shows a complete compressor unit in elevation with parts broken away.

In the embodiment shown in the drawings, all the stationary parts of the motor compressor form a unit I which comprises:

(a) three cylinders (compression cylinder llll provided with longitudinal slots I l and connected with delivery pipe I05 through outlet valves not shown in the drawings, motor cylinder I02, the ends of which are provided with cooling fins 24 and with a piece 25 screwed thereon and fitted with packing rings 26, and a second compression cylinder, similar to cylinder I0! and not shown in the drawings) (b) a chamber 2| carried by each compression cylinder, connected with the atmosphere through openings 20 provided with air inlet valves l9, and connected with the inside of the compression cylinder through a port 22; i

(c) a casing I04 inclosing a chamber l2 ex tending along the whole length of the compressor and connected with motor cylinder 102 through ports I4; I

(d) a. chamber 15 carried by each compression cylinder Ilil, connected with the inside of said cylinder through ports 30 and with chamber 12 through ports It provided with valves H;

(6) two longitudinal external recesses 8 provided on opposite sides of said casing I04, closed ,on the outer side by plates 9, and connected with chamber l5 through ports l8; said recesses are disposed along groove ll of compression cylinder lfll. 4

Two pistons such as 2 are fitted in said cylinders in such manner that their outer ends reciprocate in the compression cylinders respectively and their inner ends (of reduced section) reciprocate in motor cylinder IL The inner faces of the enlarged ends of the pistons are provided with an annular recess 21 for receiving the end of the motor cylinder. 7

The pistons are connected together through rods 3 pivoted at one end about journals 4 pro vided on the pistons, and at the other end to cranks 5' pivoted about journals 6 fitted in unit I.

Journals 4 also carry sliding members 'I adapted to reciprocate in a piston like manner in guiding recesses 8. The inner face of said sliding members is provided with a plate l0 adapted to cover the portionof groove I| located between said journal 4 and the inner end of said groove.

The operation of the apparatus will be better understood by referring to the diagram of Fig. 4 in which the pressures in one of the compression chambers are plotted in ordinates and the displacements of the corresponding piston are plotted in abscissas.

The piston starts from its innermost position corresponding to point M of thediagram. It compresses air until it reaches a position corresponding to point N of the diagram, for which valves open, thus connecting scavenging air reservoir 2 with compression cylinder l|l| through ports 30, chamber 5, and ports l6. From N to 0 the piston drives compressed air into the scavenging air reservoir. When the piston reaches a position corresponding to point 0, it closes ports II and 30 so that there is no longer any communication between the .compression cylinder and chamber i5. From 0 to P, piston 2 compresses air into the compression cylinder IOI. At point K, that is when the pressure in cylinder |0| begins to be very high, piston 2 covers port 22 so that there is no longer any connection between cylinder'llll and chamber 2|. When piston 2 reaches a position corresponding to point P, the outlet valves (not shown in the drawings) open and from P to Q air is delivered into outlet pipe I05 at a constant pressure. When piston 2 is in a position corresponding to point Q, said outlet valves are closed. :From Q to R, at the beginning of the instroke,

the cushion of compressed air remaining in the clearance space of the cylinder expands down to the atmospheric pressure. reaches a position corresponding to point R, it uncovers port 22 and inlet valves l9 open. From R to M the air from the outside enters into the compression cylinders through said inlet valves and ports 22.

During the whole of the outstroke of piston 2 small pistons compress air into chambers 8, which are always in communication with the scavenging air reservoir l2 through ports l8 and I6, said pistons I continuing to act even when pistons 2 have covered ports ll.

During the period of time for which ports 22 are covered by pistons 2 (from point K to point B. of the diagram), any connection between the inside of cylinder |0| and ports 20 is cut ofi so that no leakage of compressed air can take place through valves l9. This is a very important result in view of the high pressure existing inside cylinder l0l.

When the compressor works with its maximum power, the outstroke goes as far as Q (Fig. 4) and the expansion of the cushions of compressed air remaining. in the clearance space of the cylinder takes place as far as R, below atmospheric pressure since the connection of the inside of cylinder |0| with chamber 2| is established only when piston 2 uncovers port 22. It is-desirable to recover the lost work corresponding to the cross-hatched portion of the diagram.

Such a result can be obtained with an arrangement such as shown in Fig. 5.

According to that arrangement, piston 2 is provided with a conduit 33, 34 connecting the outer face of the piston to an intermediate point of the cylindrical wall thereof. Said conduit is provided with a valve 3| subjected to the action of a spring 32 of relatively small strength. The point at which conduit 34 opens into the When piston 2 wall of piston 2 is so chosen that when the pressure in cylinder |0| passes below the atmospheric pressure, conduit 34 is located opposite port 22, so that valve 3| opens and air can enter into cylinder 0|.

Such an arrangement has the further advantage that the compressed air present in chamber 2| during the beginning of the instroke expands, through conduit 34 and valve 3|, into cylinder H as soon as the pressure in cylinder |0| during the instroke of piston 2 becomes lower than the pressure in chamber 2| so that, when ports 22 are uncovered by piston 2 the air in chamber 2| is already expanded and valve I9 opens much more quickly. The air compressed in chamber 2| at a pressure corresponding to point K of the diagram of Fig. 4 expands into cylinder |0| during the part I--R of the instroke. Plates l0 serve to prevent the lubricating oil of pistons 1 to mix with the lubricating oil of pistons 2. While I have described what I deem to be a preferred embodiment of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of my invention as comprehended within the scope of the' appended claims.

What I claim is:

1. In a motor compressorincluding a motor cylinder, two compression cylinders disposed on opposite sides thereof and coaxially therewith, and two opposed pistons the inner ends of both of which reciprocate in the motor cylinder and of which reciprocate in the motor cylinder and the outer ends of which reciprocate in the compression cylinders respectively, the combination of a chamber provided on the outside of each compression cylinder at an intermediate point thereof, said cylinder being provided with a port at said point so as to connect its inside with said chamber, at least one inlet check valve in said chamber for allowing air from the outside to enter thereinto, each compression piston being provided with a conduit connecting its outer face with an intermediate point of the cylindrical wall thereof so located that communication is provided between said port and said conduit, a check valve provided in said conduit for allowing air to enter therethrough into said cylinder.

3. A device according to claim 2 further comprising a spring of relatively small strength for applying the lastmentioned check valve against its seat. 1

4. In a motor compressor including a motor cylinder, two compression cylinders disposed on opposite sides thereof and coaxially therewith, two opposed pistons the inner ends of both of which reciprocate in the motor cylinder and the outer ends of which reciprocate in the compression cylinders respectively, the combination of a chamber provided on the outside of each compression cylinder at an intermediate point thereoi, said cylinder being provided with a port at said point so as to connect its inside with said chamber, and at least one check valve for allowing air to pass only in one direction through said chamber.

5. In a motor compressor including .a motor cylinder having an inlet port, two compression cylinder disposed on opposite sides thereof and coaxially therewith, two opposed pistons the inner ends of both of which reciprocate in the motor cylinder and the outer ends of which reciprocate in. the compression cylinders respectively, the combination of a chamber provided on the outside oi each compression cylinder at an intermediate point thereof and communicating with said inlet port, said cylinder being provided with a port at said point so as to connect its inside with said chamber, and at least one check valve for allow-v lng air to pass only in one direction through said chamber towards said port.

RAUL PA'I'ERAS PESCARA. 

